Reaction of organic compounds with hydrogen halides



, troublesome. added directly or in solution in an organic solvent Patented Jan. 18, 1949 REACTION OF ORGANIC COMPOUNDS WITH HYDROGEN HALIDES Arthur Ira Gebhart, Union, N. J assignor to 601- gate-Palmolive-Peet Company, Jersey City,

N. J., a corporation of Delaware N Drawing. Original application April 8, 1942,

Serial No. 438,075. Divided and this application November 13, 1943, SerialNo. 510,219

Claims. 1

and sand and to pass the resulting Vapors over moist red phosphorus spread over glass wool in a U-tube, a procedure which is both long and The hydrogen bromide is then to an unsaturated compound, and the mixture frequently takes several hours in order to form the addition product. This addition procedure, besides being a tedious one, is generally unproductive either of good yields or of good quality of the product.

It is an object of the present invention to provide a new method for rapidly preparing good yields of halogenated organic compounds of high purity.

It is also an object of this invention to provide a novel process for adding anhydrous hydrogen halide, particularly anhydrous hydrogen bromide, to unsaturated organic aliphatic groups.

Other objects and advantages of the invention will be apparent from the following description.

According to the present invention, anhydrous hydrogen halide is contacted fora relatively short time with an unsaturated organic compound to be hydrohalogenated. Contact is advantageously effectuated in an inert, non-aqueous, polar medium, such as liquid sulphur dioxide, and the hydrogen halide, say hydrogen chloride or hydrogenbromide, is preferably formed in situ in the medium before contact with the organic compound. After hydrohalogenation, the liquid sulphur dioxide is removed, and the halogenated product is recovered.

The hydrogen halide (e. g., hydrogen bromide) is preferably employed in substantially anhydrous condition. A suitable method for preparing substantially anhydrous hydrogen halide has been described in the application (Serial Non.

438,075 now PatentNo. 2,339,330, issued January 18, 1944) of which thepresent case 188, division. This. method comprises contacting U a, halogen (e. g.,bromine) dissolved in. liquid sulphur dioxide with water to produce the hydrogen halide (e. g., hydrogen bromide) and sulphuric acid. In practice, a considerable excess of sulphur dioxide is advantageously used, the liquidsulphur dioxide preferably serving as a solvent for the bromine and for the hydrogen bromide formed. Chlorine may be similarly reacted to form anhydrous hydrogen chloride. It is preferred, especially when preparing hydrogen chloride by this method, that an amount of ,waterbe added at least sufiicient to react with all free halogen present, as the presence of free chlorine in subsequent halogenations may give undesired side reactions. Sulphuric acid'of concentration up to 100% has low solubility in liquid sulphur dioxide at 0 C. and lower and forms a separate lower layer which may be withdrawn, if desired, although the presence of sulphuric acid in the subsequent halogenation is frequently not disadvantageous. Indeed, in certain reactions, such as the esterification of an alcohol with, hydrogen halide, the

sulphuric acid, may serve to remove Water, thus assisting in completion of. the reaction.

-.The process:oftheinvention is applicable for hydrohalogenation, and especially for hydrobromination, of organic unsaturated compounds, particularly those of the olefinic and acetylenic types. These include unsaturated aliphatic hydrocarbons, acids, alcohols, aldehydes, ethers, ketones and the like, as well as derivatives of these compounds, including .sulphonated, nitrated, halogenated, or aryl-substituted bodies, etc., and the like. Compounds satisfactory for hydrohalogenation by the present process include propylene, d-ecene-l, 5-ch1orpentene-2, crotonylene; isoprene, diallyl (hexadiene-lj), allyl bromide, heptyne-l, styrene, vinyl acetylene, de-

hydro undecylenic acid, beta-ethyl-acrylic acid, sorbic acid, linoleic acid, maleic anhydride, cinnamic acid, cyclopentadiene, allyl carbinol, citronellol, l-nitroisobutylene 2, acrolein, propargylic aldehyde, crotyl ethyl ether, vinyl propyl ketone, mesityl oxide, phorone, indene,etc. The process of this invention is thus applicablefor reacting a hydrogen halide with anyorganic compound capable of reacting with said hydrogen halide at similar temperatures. I 3 i In contacting the unsaturated organidcompound with 3 the" liquid Sulphur dioxide l1 solution of hydrogen-halide, ithas been found convenient to run the organic compound, if liquid, into the sulphur dioxidesolution while agitating, orgfif the organic compound is gaseous, "to bubble it through the sulpjhur dioxide solution. The organic compoundif solid, may be added directly solution of hydrogen halide into the organic com pound to be hydrohalogenated, or the two bodies may be passed in countercurrent to eachiother in continuous operation. Such countercurrent' con tact is of particular convenience where the organic compound is gaseous-andcansbe bubbled. upward through a downwardly moving column oi' the sulphur dioxide solution-ofhydrogenhalide. Similarly, although it is preierredtoyprepare the hydrogen halide in the manner:- dis'closed; .it .is also contemplated that the unsaturated, organic reactant may be dissolved in liquid sulphur dioxide and that the hydrogen halide may thereafter-be'added totl'ie 'l-i'quidsulphur dioxide solutionthus formed. 'Ihehydrogen halide maybe passed in the gaseous stateinto' said solution or maybe .runinto the solution in liquefied form or dissolved "in liquid sulphur dioxide or in an organic solvent;

The organic reactants may advantageously be dissolved in another inert solvent'for admixture with *the' sulphur dioxidesolution of thehydrogen halide, especially where the reactant is insoluble or only slightlysoluble in "liquid sulphur dioxide. l

The reaction mixture may thus be of either one or two liquid phases, and itis preferred that the solvent selected be at least partly miscible with liquid sulphur dioxide; Suitable-solvents or. suspending media for 'theunsaturated organic. reactant: include-butane, pentane, hexane, decane an'dtother alkanes; carbontetrachloride; chloroform, ethylene dichloride, fiethyl bromide, .dichloro-difiuolomethane, andxother halogenated hydrocarbons; cyclohexane, decalin, 'tetralin. and other cycloalipha'tics; benzene, toluene, the xylenes, naphthalene, diphenyl, .nitrob'enzen'e and other aromatic hydrocarbons 'togetherwith. their n'itro-, halogeno-, and :other derivatives; apetroleum ethersandsgasoline;:liquidicarbondloxide;

liquidsulphur dioxide; :ethylether,- dioxaneand other ethers'; carbondisulphide'; andwthelikaan-d mixturesithereof;

The contact-of the organic reactant, withthe liquid sulphur; dioxide .isolution of the; hydrogen halide is preferably-aided ,byaagitation, especially where rmoresthan one "phase ispresent; The time or contactsvaries appreciably, depending upon the compound :tobehydrohalogenated, but ithas been observed that highyields are obtainable with most reactants afterabout. fifteen to about thirty minutes, and in some .cases in even shorter time. Similarly, the proportions of the organic reactant tocthe hydrogemhalidemayvary widely, especially .;for, different degrees. of, hydrohalogenation where poly-unsaturatedor acetylenidgroups are reacted. The reaction temperatures and pressures may also :beyaried within widelimits, again depending upon-the compound to. be reacted and theproduct tobe formed. In'general, it .is preferred to carry out the reaction at temperatures around-- 10- Cior, below randat atmospheric pressure, although-temperatures fromv about i -4.0 to

about 70 C.- or evenhigher .(butbelow the critical temperature of :sulphur dioxide) may be used.

Likewise, either ,superatmospheric or reduced :press-ures may alsobeemployed, the iormerbeing preferred: when higher temperatures are used. in

order to keep the.. sulphur dioxide. in. the liquid state. When the operation is carried out at tem- After the reaction has progressed to the desired I degree; the sulphur dioxide is removed from the ill) reaction-mixture. This may be accomplished by bubbling aninert gas, such as carbon dioxide, nitrogen, stack gases, etc, through the mixture,

and/or. by gradually pouring the mixture into ice water or uponice, during which operation most of the liquid sulphur dioxide volatilizes, and/or by other means. Suitable equipment may be provided for carrying out these operations, whereby the volatility of the sulphur dioxide may be increased, asby reducing the pressure in the system. Suclrequipment may also be provided with condensers, whereby the volatilized sulphur dioxide and/or other, solvent employedmay be recovered for reuse. Inmany cases, the nature of the product iormedis such that its temperature may be increased without deleterious effect, so that most or all of the remaining'solvent may be re:- moved from, the reaction mixture by heating or the like. Known methods, including fractional distillation, fractional crystallization, extraction, and other separation procedures or. any combination of these-may be employed for separating, the product from the aqueous mass and/or from unreacted materials.

The effect of oxidation upon olefines and other unsaturated bodies is a deleterious one for the present purpose, since, in the presence of peroxides, olefines and substituted olefines give polymeric sulphones with sulphur dioxide. It 'has therefore been found, to be of advantage to use freshlyprepared and/or freshly distilled 'olefinic and acetylenic compounds substantially free from-peroxides and/ or to add anti-oxidants to the mixtures before hydrohalogenating. Suitable anti-oxidants include 'stannous chloride, hydroquinone, pyrocatechin, decahydronaphthalene, etc; By excluding substantially all peroxides and otheroxidizing agents, it is possible to obtain a substantially homogeneous reaction product, as, when operating at the normally low temperatures of the present process, the addition of hydrogen bromide (or'hydrogen chloride) generally follows Markownikofis rule almost quantitatively, the

negative-radicle (C1 or'Br) being attached to the the invention is not limited thereto.

Example I About 250 cc. of liquid sulphur dioxide is tapped irom: an inverted. cylinder oisulphur dioxide-into a cylindrical, unsilvered Dewar flask of about 1 liter capacity, open atthe top, and provided, with an electric stirrer and with a stop cock at its lower end. About 20 gramsof bromine are added to the-liquid sulphur dioxide and are dissolved therein, the sulphur dioxide vapors acting as a blanket to keepatmospheric oxygen and moisture outofthe vessel. Aboutl'dgrams Of Water are then slowly added with stirring until the reddish brown color of the bromine is discharged. A lower layer of sulphuric acid collects at the bottom of the Dewar flask upon standing and is permitted to remain there.

About 25 grams of freshly distilled styrene is A then run into the sulphur dioxide solution in the flask, and the mixture is stirred for about thirty minutes at about -8 C. At the end of this period, substantially none of the hydrogen bromide remains in the sulphur dioxide solution. A current of carbon dioxide is then passed throuogh the reaction mixture to evaporate a major portion of the liquid sulphur dioxide, and the mixture is thereafter run into cracked ice and water. When most of the sulphur dioxide has volatilized, the residue is extracted with petroleum ether and is washed free of acids with water, the first portions of wash water used containing a small amount of sodium hydroxide. The petroleum ether is then evaporated to yield about 39.4 grams of alpha-bromoethylene as a colorless, harsh-smelling liquid. The product obtained distills at'a'bout 64 C. to about 66 C. at a pressure of 8 mm. of mercury, and the amount obtained is equivalent to about 86.5% of the calculated theoretical yield.

The structure of the product is confirmed by reacting a portion thereof with sodium acetate in acetic acid to form an. acetate, which, after saponification, yields an alcohol boiling at about 201 C. The alcohol, by conversion to the 3,5- dinitrobenzoate melting at about 92 C. to 95 0., is proven to be alpha-phenylethyl alcohol. A portion of this alcohol is oxidized with chromic acid to obtain acetophenone, recognized by the semicarbazone melting at about 196 C. It thus appears that hydrogen bromide can be added to styrene, in accordance with the procedure of the present invention, and follows the Markownikoff rule to give alpha-bromoethylbenzene.

Example II reaction mixture is slowly poured into ice water to evaporate sulphur dioxide, and the product is extracted with petroleum ether, dried and distilled. The product comprises bromophenylpropionic acid.

Example III To a solution of about 40 grams of hydrogen bromidein about 250 cc. of sulphur dioxide at about C. and at a pressure ofabout 4 atmospheres, about 55 grams of freshly distilled allyl bromide at about 20 C. is slowly added. The reaction mixture is agitated for about fifteen min utes. Nitrogen gas is then bubbled through the reaction mixture, which is then poured into ice water to volatilize the major portion of the sulphur dioxide, and thereafter the entire mass is distilled to remove residual sulphur dioxide, unreacted allyl bromide and water. The residue, boiling at about 140 C. to 142 C., comprises 1,2- dibrompropane.

Example IV About 14 grams of freshly distilled acrolein are slowly added to a solution of about grams of anhydrous hydrogen bromide in about 150 cc. of

substantially to eliminate side reactions.

Example V About 20 grams of chlorine are dissolved in about 250 cc. of liquid sulphur dioxide, and water is slowly added to form hydrogen chloride in situ. About 50 grains of indene are run into this solution, and the mixture is mechanically agitated for about thirty minutes. At the end of this time, the temperature is gradually increased, and the sulphur dioxide is distilled off. The reaction mass is then extracted with carbon tetrachloride and is further distilled, alpha-chlorindane being obtained therefrom Example VI About 23 grams of freshly distilled propargyl alcohol are slowly added to an anhydrous solution of about grams of hydrogen bromide in about 250 cc. of liquid sulphur dioxide. The mixture is stirred for about fifteen minutes, and the mixture is then poured into ice water. The The aqueous mass is extracted with carbon tetrachloride and is distilled, bromo-allyl alcohol being obtained.

Example VII An anhydrous solution of about 90 parts by weight of hydrogen bromide per hour dissolved in about 600 parts of liquid sulphur dioxide per hour are run slowly downward through a column. At a point above the lowest portion of the column, about 30 parts of ethylene per hour are passed into the column and are bubbled through the downwardly flowing solution. The reaction product is removed at the bottom of the column together with liquid sulphur dioxide, from which it is separated and recovered. The unreacted ethylene and volatilized sulphur dioxide are withdrawn at the top of the column. The product comprises ethyl bromide.

Example VIII About 42 grams of freshly distilled ethylene oxide are mixed into ananhydrous solution of about 80 grams of hydrogen bromide in liquid sulphur dioxide. Following the procedure as set forth in Example I, ethylene bromohydrin is obtained as a product.

Example IX About grams of freshly distilled propyl cyanide are slowly added with stirring to an anhydrous solution of about grams of hydrogen bromide in liquid sulphur dioxide. The procedure of Example I is followed, and a product comprised propyl imino-bromide is obtained.

The use of anhydrous hydrogen halide for these reactions is of considerable advantagein obtaining high yields and high quality of product. Liquid sulphur dioxide has many advantages as a solvent for the reactants, being inexpensive, easily removable, non-corrosive and, noninflammable and having a .low boiling-point. Close control of reaction temperatures, ordinarily unattainable or attainable only with great ane difiiculty, .can. be EBaSiIY' maintained in liquid sulhydrogen halide prepared in .themanner disclosed :herein, may also be carried out. The same procedureas shown here for hydrohalogenation of various organic compounds can be followed, or

such procedure may be modified, depending upon 1 conditions to be met and, operative expediency. Thus, hydrogen bromide in liquid sulphur dioxide may be employed-indouble decomposition and substitution reactions. Alkyl halides may be formed'by contacting alcohols with a hydrogen halide in liquid-sulphur dioxide. In like manner, hydroxyl substituted aliphatic acids may be added to solutions of a hydrogen halide in sulphur dioxide to form the corresponding halogemsubstituted acids. Hydrogen bromide in liquid sulphur dioxide can also be used as an esterification catalyst for influencing the reaction of an organic carboxylic acid with an alcohol to form an ester. Similarly, aryl halides can be formed by reaction of a hydrogen halide in liquid sulphur dioxide with aryl diazoniurn halides in the presence of a suitable catalyst; thus, benzene diazonium chloride, when. mixed with hydrogen bromide'in the presence oiliquid sulphur dioxide and cuprous bromide as a catalyst, gives a product comprising brombenzene.

Although the present invention has been described with reference to particular embodiments and examples, it will be apparent to those skilled in the art that variations and modifications of this invention can be made and that equivalents can be substituted therefor Without departing from the principles and true spirit of the inven- .tion.

Iclaim:

1. The process of. reacting organic compounds with a hydrogen halide which comprises intimately contacting, a. hydrogen halide from the group consisting of hydrogen chloride and hydrogen bromide with an organic reactant while at least one of said halide and said reactant is dissolved in liquid sulphur dioxide.

2. The process of. reacting organic compounds with a hydrogen halide Which comprises react ing a hydrogen halide from the group consisting of hydrogen chloride and hydrogen bromide with an unsaturated organic compound in liquid sulphur dioxide medium.

3. The process of reacting unsaturated organic compounds Wlthhydrogen bromide which comprises mixing. a solution of anhydrous hydrogen bromide in liquid sulphur dioxide with an unsaturated organic compound capable of adding hydrogen bromide, and removing sulphur dioxvide. fromsaid mixture.

4. The. process ofv reacting organic compounds with hydrogen bromide which comprises preparing a solution of anhydrous hydrogen bromide in liquid sulphur dioxide, intimately contactingv .5. In the process. of hydrobrominating an unsaturated organic. compound, the improvement which comprises intimately contacting said compound With anhydrous hydrogenbromide While at least, oneof said-.;r.eactants is dissolved in liquid sulphur dioxide. a

6. The improvement set forth in claim 5 Where in the unsaturated organic-compound is freshly distilled.

7. Theimprovementset r forthcin-claim5 Where in the reactantsaare. contacted; inxthe presence of an anti-"oxidant.

8. In "the processor .hydrobrominating an organic compoundxhavingian, unsaturated aliphatic group, the improvementiwhichcomprises preparing a solution ofvanhydrous hydrogen bromide in liquid sulphur dioxide, mixing: said, solution with said organic. compound, removing sulphur'dioxide fromxsaid mixturetosleave a residue,'and recovering the addition product from 'said residue.

9. In the .processi of hydrochlorinating an organic compound'having' an "unsaturated aliphatic group, the improvement which comprises preparing a solution of anhydrous hydrogen chloride in. liquid sulphur dioxide, mixing said'solution With said organic compound, removing sulphur dioxide from said mixtureto leave aresidue, and recovering the addition product from said residue. v

10. In the process of .hydrobrominating an organic compound having an unsaturated aliphatic group, the improvement which comprises preparing a solution of anhydrous hydrogen bromide in liquid sulphur dioxide, dissolving said organic compoundin a substantially inert solvent at least partially miscible with liquid sulphur dioxide to form a second solution, intimately mixing said solutions, removing sulphur dioxide from said mixture to leave a residue, and recovering the addition product from saidnresidue.

ARTHUR IRA GEBHART.

REFERENCES CITED Thefollowing references are 'of record in the of this patent:

UNITED STATES PATENTS Number Name Date j 1,087,961 Masland,. Feb. 2. L, 1914 1,518,182 Curms Dec. 9,1924 1,037,972 Suida Aug. 2, 1927 1,985,457 Nutting et al. Dec. 25, 1934 2,031,228 Reilly Feb. 18, 1936 2,099,480 Hjerpe Nov. 16, 1937 2,125,284 Chamberlainzet al. 'Aug. 2, 1938 2,140,507, Chamberlain Dec. 20, 1938 2,244,512 Brandt. June 3, i941 2,28%,4r67 Ballard; May 28, P942 2,339,330: Gebhart Jan. 18,1991

OTHER REFERENCES I Chemical Abstracts, vol.- .17, page 748 (1923) abst. of article by. Meerwein ct al; ibid., vol. 29, col. 2465 (-1935) abst. of. article by Cornog et al. Smyth: Dielectric Constant and Molecular Structure (A. C. S. Monograph No. 55), pages 13, 191-3., 

